Ampere Hours and Battery Capacity

The Capacity of a battery is the quantity of energy a battery can store and deliver. The capacity of a battery is usually indicated in terms of Ampere hours or Ah. This is also known as the rated capacity of a battery. The total energy stored in a battery can be calculated by multiplying the Ampere-hour rating with the battery voltage. Thus a 10Ah battery with 110V can store an energy of 1100Wh or 1.1kWh.

The duration of a battery is thus dependent on its discharge rate. Manufacturers provide discharge charts for their batteries. Charging and discharging rates have a major impact on the life of a battery. A battery that is discharged at a faster rate may not deliver the same amount of energy as a battery with a lesser discharge rate.
Some manufacturers specify the capacity of a battery as a function of the discharge rate.

Temperature, too, influences the capacity of a battery. Batteries at high temperatures will have a better capacity that batteries loaded at low temperatures. Extremely high temperatures, however, can cause damage to the battery and greatly reduce capacity.

In addition to these factors, age is also a factor that determines the capacity of a battery. As a battery ages, its capacity reduces.